Drainage devices and methods

ABSTRACT

A ureteral drainage stent is designed to be placed in a patient&#39;s ureter and extend into a patient&#39;s bladder. An ureteral drainage stent includes a distal region for placement in the ureter and renal cavity, and a proximal region for placement in a urinary bladder and urethra. The distal region includes an elongated member with multiple lumens and the proximal region includes multiple elongated member, each defining a lumen. At least one lumen in the distal region is in liquid communication with a lumen from the proximal region. At least two of the elongated members in the proximal region are joined at their proximal ends and form a retraction structure, a structure used for removing the stent from a patient.

TECHNICAL FIELD

This invention generally relates to medical devices for drainage offluids, and more specifically to ureteral stents.

BACKGROUND INFORMATION

Ureteral stents are used to assist urinary drainage from the kidney tothe urinary bladder in patients with a ureteral obstruction or injury,or to protect the integrity of the ureter in a variety of surgicalmanipulations. Stents may be used to treat or avoid ureteralobstructions (such as ureteral stones or ureteral tumors) which disruptthe flow of urine from the kidneys to the bladder. Serious obstructionsmay cause urine to back up into the kidneys, threatening renal function.Ureteral stents may also be used after endoscopic inspection of theureter to prevent obstruction of the ureter by swelling of the ureteralwall caused by the surgical procedure.

Ureteral stents typically are tubular in shape, terminating in twoopposing ends: a kidney distal end and a bladder proximal end. One orboth of the ends may be coiled in a pigtail or J-shape to prevent theupward and/or downward migration of the stent due, for example, tophysiological movements. A kidney end coil resides within the lumen ofthe kidney, known as the renal pelvis, and is designed to prevent stentmigration down the ureter and into the bladder. The bladder-end coilresides in the bladder and is designed to prevent stent migration upwardtoward the kidney. The bladder coil is also used to aid in retrieval andremoval of the stent. Regions such as the trigone region in the bladderand the region of the ureter near the bladder known as theureteral-vesical junction are particularly innervated and thus sensitiveto irritation by foreign objects. Commonly used bladder-end coilscontact and irritate the trigone region causing discomfort to thepatient. Similarly, the proximal region of the stent contacts theureteral-vesical junction causing irritation and discomfort to thepatient particularly during voiding. Additionally, ureteral stents,particularly the portion positioned within the ureteral-vesical junctionand inside the bladder, may produce adverse effects including blood inthe urine, a continual urge to urinate, strangury, and flank painaccompanying reflux of urine up the stent (e.g., when voiding). Sucheffects occur as pressure within the bladder is transmitted to thekidney. In short, while providing drainage from the kidney to thebladder, stents may also cause or contribute to significant patientdiscomfort and serious medical problems.

SUMMARY OF THE INVENTION

The present invention relates to a ureteral stent that reduces patientdiscomfort by reducing the flow of urine from the urinary bladder to thekidney (urine reflux) and minimizing contact between the stent andregions of the body of the patient, including the trigone region andureteral-vesical junction. In particular, the invention relates to astent with a proximal region that includes a plurality of elongatedmembers, each member defining a lumen, and a distal region that includesan elongated member defining a plurality of lumens. The proximal anddistal regions of the stent reduce urine reflux by reducing the rate atwhich urine may flow through the stent from the urinary bladder to thekidney. Additionally, the proximal and distal regions of the stentminimize the contact and abrasion between these regions of the stent andthe trigone region and ureteral-vesical junction of the patient, thusreducing patient discomfort.

The plurality of members in the proximal region are generally locatedwithin the urinary bladder when the stent is in place within the urinarytract of a patient. The plurality of elongated members form a proximalretention structure that functions to maintain the proximal regionwithin the bladder and thus restrain the migration of the stent towardsthe kidney. The shape and composition of the proximal region assist inreducing patient discomfort. The proximal retention structure is formedin a shape that minimizes contact between the elongated members of theproximal retention structure and the trigone region of the bladder, andthus reduces patient discomfort. The elongated members in the proximalregion are also sufficiently thin and flexible to minimize the force ofcontact and abrasion to the sensitive regions of the urinary tract,including the trigone region. However, the plurality of elongatedmembers that form the proximal retention structure are also sufficientlyresilient such that the shape of the proximal retention structure isgenerally maintained while the stent is in the body.

The lumens of the multiple elongated members in the proximal region alsoreduce patient discomfort caused by urine reflux by minimizing the rateat which urine may flow from the urinary bladder to the kidney. Thelumens of the multiple elongated members include sufficiently smallinner diameters to prevent the flow of urine from passing through thelumens at a rapid rate typical of urine reflux. However, the size of thelumens are sufficient to allow urine flow to from the kidney to thebladder at the slow rate typical of the naturally occurring drainagefrom the kidney to the bladder.

The distal region also reduces urine reflux by the multiple lumens inthe region preventing the rapid flow of urine, a typical cause of urinereflux. The multiple lumens in the distal region include sufficientlysmall inner diameters to restrict the rate that urine passes through thedistal region. The multiple small lumens in the distal region preventurine flow at a rate typical of urine reflux. Additionally, the multiplelumens in the distal region assist in preventing urine reflux bybecoming occluded as a result of only a moderate degree of compression,by the ureteral orifice, for example. This results from the lumens inthe multiple lumen configuration of the distal region collapsing morecompletely than, for example, a single lumen with a similar lumencapacity under an equivalent amount of compression.

In one aspect, the invention relates to a ureteral stent that includes aproximal region that includes a plurality of elongated members, each ofthe members defining a lumen extending therethrough, and a distal regiondisposed relative to the proximal region and that includes an elongatedmember defining a plurality of lumens extending therethrough. In oneembodiment, each lumen in the proximal region is in fluid communicationwith at least one of the plurality of lumens in the distal region.

In another embodiment, the distal region further comprises a distalretention structure. In one embodiment, the outer dimension of thedistal retention structure substantially perpendicular to a longitudinalaxis of the elongated member is larger than the diameter of theelongated member. This prevents the entry of the distal retentionstructure into a ureter. In another embodiment, the distal retentionstructure includes a coiled shape.

In another embodiment, at least a portion of the distal region includesan elongated member having a single lumen. The single lumen is definedby an inner wall. In a detailed embodiment, the elongated member in thedistal region includes an outer diameter ranging from about 6 to about12 French. This region of the stent may also include a biocompatibleplastic. In another embodiment, the elongated members in the proximalregion include biocompatible plastic.

In yet another embodiment, the proximal region further includes aproximal retention structure. The proximal retention structure mayinclude, in one embodiment, an outer dimension substantiallyperpendicular to a longitudinal axis of the elongated member in thedistal region that is larger than the diameter of the elongated memberin the distal region. Such an outer dimension prevents the entry of theproximal retention structure into a ureter. In one embodiment, theelongated members splay away from a longitudinal axis defined by theelongated member the distal region.

In another embodiment, the proximal region further includes a retractionstructure. In one embodiment, the retraction structure includes anelongated member attached to the plurality of elongated members in theproximal region. The retraction structure, in another detailedembodiment, includes an elongated member with an outer diameter lessthan about 3 French.

In one aspect, the invention relates to a ureteral stent that includes aproximal region that includes a plurality of elongated members, each ofthe members defining a lumen extending therethrough. The ureteral stentalso includes a distal region that includes a first portion, disposedrelative to the proximal region, that includes an elongated memberdefining a plurality of lumens extending therethrough, and a secondportion, disposed relative to the first portion, that includes anelongated member defining a lumen extending therethrough. In oneembodiment, the proximal region comprises an elongated member in fluidcommunication with the elongated member of the first portion.

In another embodiment, the second portion of the distal region furtherincludes a distal retention structure. In one embodiment, the outerdimension of the distal retention structure substantially perpendicularto a longitudinal axis of the elongated member in the second portion ofthe distal region is larger than the diameter of the elongated member inthe second portion of the distal region. This prevents the entry of thedistal retention structure into a ureter. In yet another embodiment, thedistal retention structure includes a coiled shape.

In another embodiment, the proximal region further includes a proximalretention structure. In one embodiment, the outer dimension of theproximal retention structure substantially perpendicular to alongitudinal axis of the elongated member in the distal region is largerthan the diameter of the elongated member in the first portion of thedistal region. This prevents the entry of the proximal retentionstructure into a ureter. In yet another embodiment, the proximal regionfurther includes a retraction structure. In one embodiment, theretraction structure includes an elongated member attached to theplurality of elongated members in the proximal region.

In another aspect, the invention relates to a method for draining urinefrom a kidney. The method requires inserting a ureteral stent into aureter of a patient wherein the ureteral stent includes a proximalregion including a plurality of elongated members, each said memberdefining a lumen extending therethrough, and a distal region disposedrelative to the proximal region and including an elongated memberdefining a plurality of lumens extending therethrough. The method alsorequires draining urine via at least one of the plurality of lumens ofthe distal region. In one embodiment, the stent is positioned such thatat least a portion of the distal retention structure resides within akidney. In another embodiment, the distal region further includes adistal retention structure. The distal retention structure preventsmigration of the distal end of the elongated member out of a kidney. Inanother embodiment, the method further includes positioning at least aportion of the proximal region of the ureteral stent in a urinarybladder. In yet another embodiment, the proximal region further includesa proximal retention structure. The proximal retention structureprevents migration of the proximal end of the ureteral stent out of aurinary bladder.

In another aspect, the invention relates to a method of positioning aureteral stent within a patient. The method includes providing aureteral stent as previously described. The method then includespositioning the stent within a patient using a guide wire and a pusher.The stent is mounted over a guide wire already positioned within thebody and is pushed along the guide wire utilizing a pusher to locate thestent within the ureter of a patient. The shape of the pusher,particularly the distal end of the pusher, conforms to a shape of aproximal end of the ureteral stent. This allows the pusher toeffectively transfer the necessary force to the proximal end of thestent to position the stent within the patient. Once the stent isproperly located within patient the guide wire is removed from thepatient. The pusher may also be removed from the patient after theprocedure.

In one embodiment, the method further includes inserting the guide wireinto a urinary tract of the patient. The guide wire may be inserted intothe urinary tract prior to inserting the stent into the urinary tract.In yet another embodiment, mounting the stent over a guide wire includesinserting the guide wire within a lumen of the elongated member. Inanother embodiment, the stent further includes a distal retentionstructure and the method further includes positioning the distalretention structure within a kidney. The distal retention structureprevents the stent from migrating down the ureter and into the urinarybladder. In yet another embodiment, the stent further includes aproximal retention structure and the method further includes positioningthe proximal retention structure in a urinary bladder. The proximalretention structure prevents the stent from migrating out of the bladderand up the ureter.

In another aspect, the invention relates to a method of manufacturing astent including laminating a plurality of elongated members, eachelongated member having a lumen extending therethrough, to form a firstelongated member. The method further includes bonding an end of thefirst elongated member to an end of a second elongated member with asingle lumen.

In another aspect, the invention relates to a method of manufacturing astent including laminating a plurality of elongated members, eachelongated member having a lumen extending therethrough, to form a firstelongated member. The method also includes bonding a first end of thefirst elongated member to an end of a second elongated member with asingle lumen, and bonding a second end of the first elongated member toan end of a third elongated member with a single lumen.

The foregoing and other aspects, embodiments, features, and advantagesof the invention will become apparent from the following description,figures, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like reference characters generally refer to the sameparts throughout the different views. Also, the drawings are notnecessarily to scale, emphasis generally being placed upon illustratingthe principles of the invention.

FIGS. 1A and 1B depict an embodiment of a ureteral stent of theinvention, with FIG. 1A showing the distal region of the devicepositioned in a ureter and a kidney and a proximal region of the devicein a urethra and bladder, and FIG. 1B showing the device outside of thebody.

FIGS. 2A and 2B depict an embodiment of proximal and distal regions of aureteral stent of the invention in longitudinal cross-section within theureter and urinary bladder.

FIGS. 3A-I depict cross-sectional views of various embodiments of adistal region of the ureteral stent of the invention.

FIGS. 4A-L depict cross-sectional views of various embodiments of adistal region of a ureteral stent under different types of compression.

FIGS. 5A-C depict an embodiment of a ureteral stent of the invention,with FIG. 5A showing the device outside of the body, and FIGS. 5B and 5Cshowing embodiments of a portion of the stent.

FIGS. 6A-D depict various steps involving a guide wire, a pusher and aureteral stent in longitudinal cross-section positioned in the ureterand urinary bladder, as occurs during installation of the stent.

DESCRIPTION

This invention generally relates to a ureteral stent that minimizesdiscomfort when positioned within a urinary tract of a patient. Thestent of the present invention includes a distal region that includes anelongated member defining multiple lumens. The elongated member of thedistal region is connected to a proximal region that includes multipleelongated members, each member defining a lumen. The stent of theinvention, due to its dimensions, shape, and rigidity, minimize theforce of contact and abrasion to sensitive areas of the urinary tract,including the trigone region of the bladder and ureteral-vesicaljunction. Additionally, the stent of the invention, due to the multiplelumens in the proximal region and at least a portion of the distalregion, reduces urine reflux by reducing the total capacity of thelumens and by facilitating the occlusion of the lumens duringcompression of the distal region.

Referring to FIGS. 1A and 1B, a ureteral stent 100 includes a distalregion 102 that includes an elongated member defining multiple lumens101. The stent 100 also includes a proximal region 106 with multipleelongated members 111, (two are depicted) each defining a lumen 103. Thelumens 103 of the multiple elongated members 111 are in fluidcommunication with a lumen 101 of the elongated member of the distalregion 102. The elongated members 111 of the proximal region 106 includeopenings 109, such as slits or holes in the walls of the elongatedmembers 111, for example, to allow urine to drain from the members.Drainage of urine from the renal pelvis 110 to the bladder 112 occurs bythe movement of urine into an opening at a distal end of the elongatedmember of the distal region 102, followed by the urine passing throughthe distal region 102. The urine then enters and flows through thelumens 103 of the multiple elongated members 111 until reaching theopenings 109 in the elongated members 111. Urine may flow out of theopenings 109 and into the bladder 112. The urine may then be expelledfrom the body under the natural control of the patient.

The elongated member of the distal region 102 is located within theureter 108 and renal pelvis 110 when the stent 100 is positioned in thepatient. A portion of the stent 100 at the distal end of the elongatedmember of the distal region 102 forms a distal retention structure 104.The distal retention structure 104 is located in the renal pelvis 110and functions as an anchor to prevent the migration of the stent 100 outof the renal pelvis 110 and down the ureter 108. The shape of the distalretention structure 104 may be a coil (shown), a pig-tail coil,J-shaped, or a helical coil, for example.

The elongated members 111 are located within the urinary bladder 112when the stent 100 is positioned in the patient. The elongated members111 form a proximal retention structure 115 that functions in retainingthe proximal region 106 in the bladder 112 and thus preventing themigration of the stent 100 up the ureter 108. At a proximal end of theproximal region 106 may exist a retraction structure 107. The retractionstructure 107 is positioned in the urethra 120 and extends outside ofthe patient when the stent 100 is positioned in the patient.

The stent 100 of the present invention reduces patient discomfort byminimizing the force of contact and abrasion between the stent 100 andthe ureteral-vesical junction 114 and trigone region of the urinarybladder wall 116. The elongated members 111, due to their presence inthe bladder 116 when the stent in use, may make contact with the trigoneregion. The elongated members 111 are generally of minimal diameter,flexible and light in weight thus causing the elongated members 111 tobe less irritating or abrasive to the trigone region. The outerdiameters of the elongated members 111 and the width of the wallsforming the elongated members 111 are sufficiently small to minimize theforce of contact and abrasion of the elongated members 111 on the trigone region of the bladder 112. The elongated members 111 are alsosufficiently resilient to maintain a shape suitable to function as aproximal retention structure 115. The elongated members 111 may beformed in various shapes to produce a proximal retention structure 115that minimizes contact with the trigone region and prevents the movementof the ureteral stent 100 up the ureter 108. The proximal retentionstructure 115, formed by the elongated members 111, includes an outerdimension greater than the diameter of the ureter 102, thus preventingthe proximal retention structure 115 from entering the ureter 102. Theelongated members 111 also are joined at the proximal end of theproximal region 106 to form a retraction structure 107. The retractionstructure 107, an elongated thread-like member, which need not containlumens, passes into the urethra 120 from the bladder 112 and extendsalong the urethra 120 and out of the body of the patient. The retractionstructure 107 can be used to withdraw the stent 100 from the patient.

The stent 100 also minimizes patient discomfort associated with urinereflux by assisting in the prevention of urine flow through the stent100 from the bladder 112 into the renal pelvis 110. During urine refluxthrough the stent 100, urine must flow into the openings 109 and throughthe lumens 103 of the elongated members 111 to reach the distal region102. The elongated members 111 assist in preventing urine reflux byobstructing the rapid passage of urine from the bladder 112 to thedistal region 102 of the stent 100. The openings 109 of the elongatedmembers 111, depending on their size, shape and number, may restrict theflow of urine to varying degrees. Reducing the size or number of theopenings 109 reduces the rate at which urine may flow into the lumens103 from the bladder 112. Openings 109 consisting of slits are less openthan holes or windows in the elongated members 111 and may restricturine flow to a greater degree. The diameter of the lumens 103 of theelongated members 111 also affects urine flow. Generally, a reduction indiameter of the lumens 103 reduces the rate of urine flow through thelumens 103. Additionally, the flexibility of the elongated members 111affects urine flow. Increased flexibility in the elongated members 111allows the walls of the elongated members 111 to collapse more easily,causing occlusion of the lumens 103 and preventing urine flow. Thesemany characteristics of the elongated members 111 determine the degreeto which the route from the bladder 112 to the distal region 102 isrestricted or obstructed by the elongated members 111. Thecharacteristics of the elongated members 111 are chosen to provideadequate drainage of urine from the renal pelvis 110 to the bladder 112,to which urine generally flows at a slow rate by wicking or dripping,while acting as a barrier to the rapid flow of urine from the bladder112 to the renal pelvis 110, as occurs during urine reflux.

The elongated member of the distal region 102 and the proximal region106 may be constructed of a biocompatible plastic such as but notlimited to any of polyester, nylon based biocompatible polymers,polytetrafluoroethylene polymers, silicone polymers, polyurethanepolymers, polyethylene polymers, and thermoplastic polymers. The wall ofthe elongated member of the distal region 102 is of sufficient thicknessto resist the pressure from the adjacent tissue caused by a tumor,peristalsis, or swelling, for example, that would collapse the ureter108 if not for the presence of the stent 100. The renal pelvis 110 andthe majority of the ureter 108 are relatively insensitive to irritationby the presence of foreign objects. This allows the elongated member ofthe distal region 102, which contacts these relatively insensitiveregions of the body, to be of relatively large outer diameter andconstructed of a relatively stiff material. For example, the outerdiameter of the elongated member of the distal region 102 may range from6-8 French. An acceptable outer diameter of the elongated member of thedistal region 102 may also range from 6-12 French, for example. Thelength of the elongated member of the distal region 102 may varydepending on the size of the patient. An acceptable length of theelongated member in the distal region 102 positions the proximal end ofthe distal region 102 at a ureteral orifice 121 to the bladder 116. Thelength of the elongated member of the distal region 102 may range from20-28 cm, for example. The length of elongated members 111 and theretraction structure 107 in the proximal region 106 may also varydepending on the size of the patient. The elongated members 111 are ofsufficient length to form a proximal retention structure 115 that iseffective in preventing the upward migration of the stent 100 towardsthe renal pelvis 110. The length of the elongated members 111 may rangefrom 4-8 cm, for example. The proximal ends of the proximal region 106may be heat laminated and then stretched to form a retraction structure107. The stretching process may produce a retraction structure 107lacking lumens 101 and including an outer diameter smaller than an outerdiameter of an elongated member 111. The length of the retractionstructure 107 is sufficient to extend along the urethra 120 from thebladder 112 to outside the patient. The outer diameter of the retractionstructure 107 is sufficiently small to not prevent a sphincter fromconstricting the urethra 120 in order to block the flow of urine. Theouter diameter of the retraction structure 107 may be less than about 3French, for example.

FIGS. 2A and 2B illustrate cross-sectional representations of twoembodiments of the stent 100 at the junction of the distal region 102and proximal region 106, in portions of the ureter 108 and bladder 112.The cross section of the embodiment of the distal region 102 in FIGS. 2Aand 2B occurs at the plane 113 (FIG. 3A). In FIG. 2A, all three lumens101 depicted in the distal region 102 are in fluid communication withthe lumens 103 in the elongated members 111. In FIG. 2B, one of thelumens 101 depicted is not connected too or in fluid communication withan elongated member 111. This lumen 101 in the distal region 102 that isnot connected to an elongated member 111 may receive a guide wire orother device during the placement of the stent 100 into the body. Alumen 101 not connected to an elongated member 111 also allows for amore unrestricted flow of urine, and thus a potentially increased rateof urine flow through the lumen 101 and stent 100. Additionally, a lumen101 unattached to an elongated member 111 may allow for easier thepassage of stones or calculi through the stent 100.

The elongated member of the distal region 102 minimizes patientdiscomfort by reducing urine reflux from the bladder 112 to the renalpelvis, particularly during voiding of the bladder. When the stent 100is in place in the body, a portion of the elongated member of the distalregion 102 traverses the ureteral orifice 121 to the bladder 112. Theureteral orifice 121 constricts during voiding of the bladder 112, andthus compresses the portion of the elongated member of the distal region102 that traverses it. This compression causes the lumens 101 of theelongated member of the distal region 102 to collapse, thus preventingthe flow of urine from the bladder 112 to the kidney that causes urinereflux. The multiple lumens 101 of the distal region 102, as compared toa single larger lumen, increase the ability of the stent 100 to seal offurine from entering the kidney during urine reflux.

Referring to FIGS. 3A-I, various configurations of the lumens 101 mayexist in the distal region 102. The various configurations may includedifferent numbers of lumens 101 of various sizes in the distal region102. The lumen capacity of the distal region 102 is herein defined asbeing proportional to the total lumen area represented in across-sectional view of the distal region 102 (FIGS. 3A-3I). The innerdiameters or dimensions, the number, and the arrangement of the lumens101 within the elongated member of the distal region 102 may be variedto alter the rate of urine flow through the stent, the amount that lumencapacity decreases during compression of the distal region 102, and thedegree that the distal region 102 irritates the ureteral-vesicaljunction. The shape of the lumens 101 may be circular, rectangular, andwedge-shaped, for example. Lumens 101 may be shaped specifically toreceive or to be compatible with guide wires, cannula, or other devices.The maximum rate of urine flow through the stent is substantiallyproportional to the lumen capacity. Increasing the number and size ofthe lumens 101 increases lumen capacity.

Referring to FIGS. 4A-4L, the amount that lumen capacity decreasesduring compression of the distal region 102 is also affected by thenumber and size of the lumens 101, as well as by their shape andconfiguration. An increase in lumen 101 number and a decrease in lumen101 size generally assist in decreasing lumen capacity duringcompression of the distal region 102. For example, an elongated memberin the distal end 102 with a large single lumen (FIG. 4A) when exposedto a constricting force (FIG. 4E) or a flattening force (FIG. 4I) doesnot collapse in a manner that substantially occludes the lumen 101. Incontrast, examples of elongated members in the distal end 102 withmultiple lumens (FIG. 4B-4D) when exposed to a constricting force (FIG.4F-4H) or a flattening force (FIG. 4J-4L) do collapse in a manner thatsubstantially occludes the lumens 101. The increased ability of themulti-lumen elongated member to collapse and occlude the lumens underintermediate states of compression allows the stent to reduce urinereflux and thus improve patient comfort. Generally, shapes andconfigurations of the lumens 101 that cause the walls of the lumens 101to substantially collapse the lumen 101 under a minimal amount ofcompression of the distal region 102 are the subject of the presentinvention. FIGS. 3A-F depict various embodiments of shapes andconfigurations of the lumens 101 that represent a distal region 102,that upon a minimal degree of compression, becomes occluded due to thecollapse of the lumens 101. Many variations to the embodiments of thedistal region 102 (FIGS. 3A-I) that function similarly are feasible.

The degree that the elongated member of the distal region 102 irritatesthe ureteral-vesical junction is decreased generally by an increase inthe number and size of the lumens 101 in the distal region 102. FIG. 3Fdepicts an example of such a distal region 102 that includes arelatively large lumen capacity and a correspondingly small amount ofstructure defining the lumens 101. A distal region 102 with a lesseramount of structure defining the lumens 101 is generally more supple andcompressible, and thus less abrasive or irritating to the surroundingtissue of the ureteral-vesical junction. The relative softness of thematerial comprising the distal region 102 may be chosen in coordinationwith the configuration of the lumens 101 to achieve the desired physicalcharacteristics in the distal region 102.

A distal region 102 with a relatively larger lumen 101, as depicted inFIGS. 3E and 3F, may allow for the passage of objects such as stones orcalculi that would otherwise be caught in a smaller lumen 101. Such alumen 101 intended for transporting stones may not be connected to anelongated member in the proximal region, thus preventing stones frombecoming trapped within an elongated member in the proximal region.Alternatively, a lumen 101 intended for transporting stones may beconnected to an elongated member that includes an open proximal end andthat is not attached to the retraction structure.

FIGS. 5A and 5B depict a stent 100 that does not include multiple lumens101 along the entire length of the elongated member of the distal region102. The enlargement of a portion of the distal region 102 (FIGS. 5B and5C) depict the junction of a first portion 105 of the distal region 102,that includes multiple lumens 101, with a remaining second portion ofthe distal region 102, that includes a single lumen 101. The firstportion 105 and the second portion of the distal region 102 may beconnected as the second portion partially overlaps and is bonded to thefirst portion 105. The multiple lumens 101 in the first portion 105assist in the occlusion of the lumen capacity, and thus functions tostem the flow of urine through the stent 100. A single lumen 101 in thesecond portion of the distal region 102 potentially allows for a largerlumen capacity and thus a greater rate of urine flow through the stent100 than would be allowed if the second portion of the distal region 102included multiple lumens 101. A single lumen 101 in the second portionof the distal region 102, which may include the majority of the distalregion 102, also makes less likely the occlusion of the lumen 101 by oneor more stones or other objects becoming trapped in the lumen 101.Additionally, the single lumen 101 in the second portion of the distalregion 102 is less likely to be collapsed and occluded by a compression,caused by the surrounding tissue of the ureter, for example. Thus, asingle lumen 101 extending along the second portion of the distal region102 increases the ability of the stent 100 to drain urine and stonesfrom the renal pelvis to at least the ureteral orifice.

The manufacture of a stent 100, which includes a different wallthickness and/or composition in the second portion of the distal region102 than in the proximal region 106, is simplified when the stent 100 isconstructed from two or more segments as depicted in FIGS. 5A-C. Inconstructing the stent 100, the number of elongated members 111, theirwall thickness, and their composition is selected to maximize thefunctions of the proximal region 106. A plurality of elongated members111 are laminated, by heating, for example, along their distal end toform a relatively short elongated member with multiple lumens 101connected to the elongated members 111 of the proximal region 106. Therelatively short elongated member with multiple lumens 101 forms thefirst portion 105 of the distal region 102. The first portion 105 isbonded to the second portion of the distal region 102 to form the stent100 (FIGS. 5A and 5B). In another embodiment, the first portion 105 isconstructed by the lamination of a plurality of relatively shortelongated members resulting in a relatively short elongated member withmultiple lumens 101. The relatively short elongated member with multiplelumens 101 forms the first portion 105 and is bonded to the proximalregion 106 and to the second portion of the distal region 102 (FIG. 5C).This allows the three segments (second portion of the distal region 102,first portion 105, and proximal region 106) to be individuallyconstructed to different specifications and with different materials andsubsequently assembled into a single stent 100. Additionally, heatingand extruding a proximally located portion of the proximal region 106may form a retraction structure 107.

Referring to FIGS. 6A-D, the method of positioning a ureteral stent 100within a patient is illustrated in a schematic with cross-sectionalviews of portions of the ureter 108 and urinary bladder 112. Drainingurine from the kidney or ureter 108 may be accomplished by inserting aureteral stent 100 according to the invention over a guide wire 122 witha pusher 124, through the urethra and urinary bladder 112 to the finalposition in the ureter 108. A guide wire 122 (FIGS. 6A and 6B) assistsin the installation of the stent 100 by providing a mechanical means ofdirecting the stent 100 into the patient. The guide wire 122 is insertedinto the body, through the urinary bladder 112 and ureter 108 untilreaching the renal pelvis (FIG. 6A). Once the guide wire 122 ispositioned in the patient, the stent 100 is inserted into the patientover the guide wire 122, which remains outside the body (FIG. 6B). Thedistal retention structure 104 is straightened as the guide wire 122 isinserted through a lumen 101 without an attached elongated member 111,and the stent 100 is moved along the length of the guide wire 122 andinto the body with a pusher 124. The guide wire 122 may not enter theproximal region 106 at any time. Rather, the proximal region 106,including the elongated members 111 and the retraction structure, ispositioned in the body as a result of being attached to the elongatedmember of the distal region 102.

Once the ureteral stent 100 is properly positioned, the guide wire 122may be removed (FIG. 6C). The ureteral stent 100 may also be insertedinto the patient by use of an endoscope, ureteroscope, or a cytoscope,for example. Once the guide wire 122 is removed, the pusher 124 may bewithdrawn from the body of the patient (FIG. 6D).

Referring to FIG. 1A, the distal retention structure 104 is constructedfrom resilient material that regains its initial shape after distortion.The distal retention structure 104 assumes its predetermined shapewithin the renal pelvis and thus prevents the stent 100 from migratingdown the ureter 108. The outer dimension of the distal retentionstructure 104 is larger than the outer diameter of the elongated memberof the distal region 102. The proximal retention structure 115 formed bythe elongated members 111 is located in the bladder 112.

Referring again to FIGS. 2A, 2B, and 3A-I, the proximal region 106 mayadopt a variety of shapes and configurations. Referring to FIGS. 6B and5C, the pusher 124 abuts and applies a force against the proximal end ofthe elongated member of the distal region 102 to push the stent 100 intothe body of the patient. To facilitate positioning of the stent 100 inthe patient's body, the distal end of a pusher 124 conforms to theproximal end of the elongated member of the distal region 102. Inparticular, the distal end of a pusher 124 accommodates the multipleelongated members 111 that attach to the proximal end of the elongatedmember of the distal region 102. This allows for the force applied tothe pusher 124 to be effectively transferred to the ureteral stent 100during installation of the stent 100. Additionally, the lumen of thepusher 124 is large enough to house the guide wire 122 (FIG. 6B).

Referring again to FIGS. 1A and 1B, the distal region 102 and proximalregion 106 are constructed of a biocompatible plastic such as but notlimited to any of polyester, nylon based biocompatible polymers,polytetrafluoroethylene polymers, silicone polymers, polyurethanepolymers, polyethylene polymers, and thermoplastic polymers.

Referring to FIGS. 5A and 5B, the construction of the stent 100 includesbonding a component that includes the proximal region 106 and theportion 105 of the distal region 102 comprising multiple lumens 101, tothe single lumen 101 portion of the distal region 102. Additionally,portion 105 may also be bonded to the proximal region 106 (FIG. 5C). Thebonding of these components may be performed by heat bonding. Heatbonding functions by partially melting the plastic of a structure,allowing the melted plastic to adhere to a contacting surface orcomponent, and allowing the plastic to cool and harden and thus form abond. Heat bonding methods that include radio frequency bonding,induction heating and conduction heating may be used. The plastic of afirst component may be selected to melt at a similar temperature as asecond component so that both components are melted during the heatbonding process. Alternatively, either the first or second component maybe constructed from plastic with a lower melting temperature than theother component in order that only the component with the lower meltingtemperature may melt during the bonding process.

Alternatively, the components may be bonded by the use of a bondingsolvent, such as cyclohexanone and methylethylketone, for example. Thebonding solvent acts by dissolving and swelling the plastic of thecomponents. As the plastic of the components dissolve and swell, thecomponents adhere to each other. The solvent is then removed allowingfor the dissolved and swollen plastic to harden and thus complete thebonding process.

Having thus described certain embodiments of the present invention,various alterations, modifications, and improvements will be apparent tothose of ordinary skill. Such alterations, modifications, andimprovements are intended to be within the spirit and scope of theinvention. Accordingly, the foregoing description of embodiments of theinvention is not intended to be limiting.

1. A ureteral stent comprising: a distal region including an elongatedmember defining a longitudinal axis and at least one lumen that isconfigured to convey liquid; and a proximal region in fluidcommunication with the distal region and comprising a proximal retentionstructure that includes a plurality of elongated members that splay awayfrom the longitudinal axis of the elongated member of the distal regionto help prevent entry of the proximal retention structure into a ureter,at least two of the elongated members of the proximal region having alumen extending therethrough each of which is configured to conveyliquid and is in fluid communication with the at least one lumen of theelongated member of the distal region, a distal end of a first elongatedmember from the plurality of elongated members of the proximal retentionstructure being coupled to a distal end of a second elongated memberfrom the plurality of elongated members of the proximal retentionstructure, a proximal end of the first elongated member from theplurality of elongated members of the proximal retention structure beingcoupled to a proximal end of the second elongated member from theplurality of elongated members of the proximal retention structure, acentral portion of the first elongated member from the plurality ofelongated members of the proximal retention structure being unattachedfrom a central portion of the second elongated member from the pluralityof elongated members of the proximal retention structure, a portion ofthe first elongated member of the plurality of elongated members of theproximal retention structure being configured to be disposed in abladder, the portion of the first elongated member of the plurality ofelongated members of the proximal retention structure defining anopening such that the lumen of the first elongated member is in fluidcommunication with the bladder.
 2. The ureteral stent of claim 1,wherein an outer dimension of the plurality of elongated members isgreater than a diameter of the ureter.
 3. The ureteral stent of claim 1,wherein the plurality of elongated members includes an outer dimensionsubstantially perpendicular to the longitudinal axis of the elongatedmember of the distal region.
 4. The ureteral stent of claim 1, whereinthe plurality of elongated members of the proximal region aresufficiently resilient to generally maintain a shape of the proximalretention structure.
 5. The ureteral stent of claim 1, wherein theproximal region includes a retraction structure coupled to at least oneof the elongated members from the plurality of elongated members of theproximal retention structure.
 6. The ureteral stent of claim 1, whereinthe proximal region includes a retraction structure, a distal end of theretraction structure coupled to at least one of the elongated membersfrom the plurality of elongated members of the proximal retentionstructure, a proximal end of the retraction structure configured to bedisposed outside of a body.
 7. The ureteral stent of claim 1, whereinthe opening is defined by a side wall of the portion of the firstelongated member, the opening having a length that is substantiallygreater than a width of the opening.
 8. The ureteral stent of claim 1,wherein the central portion of the first elongated member from theplurality of elongated members of the proximal retention structure isbiased away from the central portion of the second elongated member fromthe plurality of elongated members of the proximal retention structure.9. The ureteral stent of claim 1, wherein the central portion of thefirst elongated member from the plurality of elongated members of theproximal retention structure is movable with respect to the centralportion of the second elongated member from the plurality of elongatedmembers of the proximal retention structure.
 10. A ureteral stent,comprising: a distal region including an elongated member defining alongitudinal axis and at least one lumen that is configured to conveyliquid; and a proximal region in fluid communication with the distalregion and comprising a proximal retention structure that includes aplurality of elongated members, a central portion of a first elongatedmember from the plurality of elongated members being unattached andbiased away from a central portion of a second elongated member from theplurality of elongate members, the plurality of elongated members beingsufficiently resilient to generally maintain a shape of the proximalretention structure while the stent is in a patient's body, at least twoof the elongated members of the proximal region including a side wallthat defines a lumen configured to convey liquid and an opening having alength that is substantially greater than a width of the opening. 11.The ureteral stent of claim 10, wherein an outer dimension of theproximal retention structure is greater than a diameter of a ureter. 12.The ureteral stent of claim 10, wherein at least two of the lumens ofthe elongated members of the proximal region are in fluid communicationwith the at least one lumen of the elongated member of the distalregion.
 13. The ureteral stent of claim 10, wherein: the at least onelumen is a first lumen; and the elongated member of the distal regiondefines a second lumen, the first lumen in fluid communication with thelumens of the at least two elongated members of the proximal region, thesecond lumen in fluid communication with a bladder.
 14. The ureteralstent of claim 1, wherein the central portion of the first elongatedmember is separated from the central portion of the second elongatedmember.
 15. The ureteral stent of claim 1, wherein the central portionof the first elongated member is movable with respect to the centralportion of the second elongated member.
 16. The ureteral stent of claim10, wherein a distal end of the first elongated member is coupled to adistal end of the second elongated member, a proximal end of the firstelongated member is coupled to a proximal end of the second elongatedmember, and the central portion of the first elongated member isseparated from the central portion of the second elongated member of theproximal region.
 17. A ureteral stent comprising: a distal region havingan elongated member, the elongated member having at least a first lumen,a second lumen and a third lumen configured to convey liquid, the distalregion defining an opening to provide fluid communication between thethird lumen and a bladder, the distal region including a coil shapedretention structure; and a proximal region having a first elongatedmember and a second elongated member, the first elongated member and thesecond elongated member each having a lumen configured to convey liquid,the first lumen of the elongated member of the distal region being influid communication with the lumen of the first elongated member of theproximal region, the second lumen of the elongated member of the distalregion being in fluid communication with the lumen of the secondelongated member of the proximal region, the first elongated member andthe second elongated member of the proximal region each including a sidewall defining an opening having a length that is substantially greaterthan a width of the opening.
 18. The ureteral stent of claim 17, whereina portion of the first elongated member of the proximal region isdisposed apart from a portion of the second elongated member of theproximal region.
 19. The ureteral stent of claim 17, wherein the firstelongated member of the proximal region and the second elongated memberof the proximal region are configured to help retain the proximal regionwithin the bladder.
 20. The ureteral stent of claim 17, wherein thefirst elongated member of the proximal region and the second elongatedmember of the proximal region are configured to splay away from alongitudinal axis of the distal region to help prevent entry of theproximal region into a ureter.
 21. The ureteral stent of claim 17,wherein a diameter of the third lumen of the elongated member of thedistal region is larger than a diameter of the first lumen of theelongated member of the distal region and a diameter of the second lumenof the elongated member of the distal region.
 22. The ureteral stent ofclaim 17, wherein a diameter of the third lumen of the elongated memberof the distal region is configured to convey a kidney stone.
 23. Theureteral stent of claim 17, wherein a distal end of the first elongatedmember of the proximal region is coupled to a distal end of the secondelongated member of the proximal region, a proximal end of the firstelongated member of the proximal region is coupled to a proximal end ofthe second elongated member of the proximal region, and a centralportion of the first elongated member of the proximal region is biasedaway from a central portion of the second elongated member of theproximal region to help prevent entry of the proximal region into aureter.
 24. The ureteral stent of claim 17, wherein a distal end of thefirst elongated member of the proximal region is coupled to a distal endof the second elongated member of the proximal region, a proximal end ofthe first elongated member of the proximal region is coupled to aproximal end of the second elongated member of the proximal region, anda central portion of the first elongated member of the proximal regionis separated from a central portion of the second elongated member ofthe proximal region to help prevent entry of the proximal region into aureter.
 25. The ureteral stent of claim 17, wherein a distal end of thefirst elongated member of the proximal region is coupled to a distal endof the second elongated member of the proximal region, a proximal end ofthe first elongated member of the proximal region is coupled to aproximal end of the second elongated member of the proximal region, anda central portion of the first elongated member of the proximal regionis movable with respect to a central portion of the second elongatedmember of the proximal region to help prevent entry of the proximalregion into a ureter.